Dear Users,
I am currently learning to use the ReaxFF forcefield in the simulation of Ethylene Carbonate molecules using LAMMPS. I am trying to reproduce results from this research paper. However, when I try to run a basic simulation with 4 replicated ethylene carbonate molecules using the following input script, I find that the molecules explode into atoms and sometimes form unphysical structures (more than two bonds for H, 3 for O, etc.).
Intialization
units real
dimension 3
boundary p p p
atom_style charge
Atom Definition
read_data OvitoEC.data
dump dumpXYZ all xyz 100 mydump.EC
replicate 2 2 2
Defining ReaxFF style/coeff
pair_style reax/c NULL checkqeq yes enobonds yes
pair_coeff * * ffield.reax.new H C O
Settings
neigh_modify delay 0 every 1 check yes
#velocity all create 298.15 4928459 rot yes mom yes dist gaussian
fix 1 all nve
fix 2 all qeq/reax 1 0.0 10.0 1e-6 reax/c #param.qeq
fix 3 all temp/berendsen 10 10 50.0
#Write data file for test
write_data ECtest.data
timestep 0.01
Output
thermo_style one
thermo 100
Run the simulation
run 100000
I also receive this warning, “VdWaals-parameters for element O indicate inner wall+shielding, but earlier atoms indicate different vdWaals-method. This may cause division-by-zero errors. Keeping vdWaals-setting for earlier atoms. (src/USER-REAXC/reaxc_ffield.cpp:259)”
However, I have tested with other applicable reaxFF files, and these result in the same disintegration of the molecules as well (without getting the above warning), which leads me to believe that it is to do with the input script. I have also tried with/out having a velocity defined, thermostat at different temperatures, and using a single molecule as well with the same result.
Any suggestion/s to overcome this issue is most welcome.
Thank you for your time.
Regards,
Don Peiris
output.text (145 KB)
OvitoEC.data (471 Bytes)
ffield.reax.new (12 KB)